My invention relates to a fastener-washer combination and, more particularly, to a fastener-washer combination which is adapted to secure a thin workpiece to a support member.
There has been a major change in the last 25 years from a wood on wood exterior building construction to a metal sheet on wood or a metal sheet on steel construction. Wood has the ability to seal a fastener; however, metal sheeting requires a resilient seal under the head of the fastener to provide a proper seal. Neoprene washers and O-rings now used provide highly elastic compression seals but do not provide a good tensile or a good slip resistant joint. In the case of nail fasteners driven into wet wood, the nail will often pop out as much as 0.05 inch when the wood dries causing the joint to leak. In the case of screw fasteners, automatic driving tools tend to over or under drive the fastener especially when used on a high productivity basis. Both an over drive or under drive condition can also create leaks with the standard fastenerwasher combination.
Fasteners, per se, having the head connected to the shank through a conical or curved surface are already known in the art, e.g. U.S. Pat. No. 3,221,588, but these fasteners are utilized without resilient washers for different applications and function differently in their particular environment. In addition, fasteners with integrally connected washers are known, e.g. U.S. Pat. No. 3,247,752, but such fasteners do not interact with the washer portion in the manner of applicant's invention.